NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study

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In order to study the effect of substituents on the preferential keto/enol forms of six mono-substituted 2-OH-pyridines, the energies corresponding to their DFT-optimized structures for both tautomeric forms were compared. To obtain an idea of how solvent dielectric effects affect such a tautomeric...

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Autores principales: De Kowalewski, D.G., Contreras, R.H., Díez, E., Esteban, A.
Formato: JOUR
Materias:
Computational geometry
Concentration (process)
Dielectric materials
Fermi level
Molecular physics
Nuclear magnetic resonance
Paramagnetic resonance
Probability density function
Solubility
Ultraviolet detectors
Gas phase
Liquid phase
Scalar coupling analysis
Tautomeric equilibrium
Organic solvents
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00268976_v102_n23-24_p2607_DeKowalewski
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_00268976_v102_n23-24_p2607_DeKowalewski
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spelling todo:paper_00268976_v102_n23-24_p2607_DeKowalewski2023-10-03T14:37:15Z NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study De Kowalewski, D.G. Contreras, R.H. Díez, E. Esteban, A. Computational geometry Concentration (process) Dielectric materials Fermi level Molecular physics Nuclear magnetic resonance Paramagnetic resonance Probability density function Solubility Ultraviolet detectors Gas phase Liquid phase Scalar coupling analysis Tautomeric equilibrium Organic solvents In order to study the effect of substituents on the preferential keto/enol forms of six mono-substituted 2-OH-pyridines, the energies corresponding to their DFT-optimized structures for both tautomeric forms were compared. To obtain an idea of how solvent dielectric effects affect such a tautomeric equilibrium, geometry optimizations were performed considering both an isolated molecule and an infinitely diluted dimethylsulfoxide solution (ε = 46.7). It was found that, for all these compounds, the dielectric solvent effect tends to increase the presence of the keto form. NMR 1J( 13C,13C) and 3J(13C,13C) isotropic couplings were measured for the same mono-substituted 2-OH-pyridines as well as for the corresponding mono-substituted pyridines. These isotropic coupling constants were also calculated within the DFT framework, where all four isotropic contributions, Fermi contact, spin dipolar, paramagnetic spin-orbit and diamagnetic spin-orbit, were taken into account. For the mono-substituted-2-OH-pyridines studied in this work, coupling constants were calculated using both the optimized keto and enol forms. The possible use of these couplings as probes to detect the keto and enol forms is discussed. Fil:Contreras, R.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00268976_v102_n23-24_p2607_DeKowalewski
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Computational geometry
Concentration (process)
Dielectric materials
Fermi level
Molecular physics
Nuclear magnetic resonance
Paramagnetic resonance
Probability density function
Solubility
Ultraviolet detectors
Gas phase
Liquid phase
Scalar coupling analysis
Tautomeric equilibrium
Organic solvents
spellingShingle Computational geometry
Concentration (process)
Dielectric materials
Fermi level
Molecular physics
Nuclear magnetic resonance
Paramagnetic resonance
Probability density function
Solubility
Ultraviolet detectors
Gas phase
Liquid phase
Scalar coupling analysis
Tautomeric equilibrium
Organic solvents
De Kowalewski, D.G.
Contreras, R.H.
Díez, E.
Esteban, A.
NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study
topic_facet Computational geometry
Concentration (process)
Dielectric materials
Fermi level
Molecular physics
Nuclear magnetic resonance
Paramagnetic resonance
Probability density function
Solubility
Ultraviolet detectors
Gas phase
Liquid phase
Scalar coupling analysis
Tautomeric equilibrium
Organic solvents
description In order to study the effect of substituents on the preferential keto/enol forms of six mono-substituted 2-OH-pyridines, the energies corresponding to their DFT-optimized structures for both tautomeric forms were compared. To obtain an idea of how solvent dielectric effects affect such a tautomeric equilibrium, geometry optimizations were performed considering both an isolated molecule and an infinitely diluted dimethylsulfoxide solution (ε = 46.7). It was found that, for all these compounds, the dielectric solvent effect tends to increase the presence of the keto form. NMR 1J( 13C,13C) and 3J(13C,13C) isotropic couplings were measured for the same mono-substituted 2-OH-pyridines as well as for the corresponding mono-substituted pyridines. These isotropic coupling constants were also calculated within the DFT framework, where all four isotropic contributions, Fermi contact, spin dipolar, paramagnetic spin-orbit and diamagnetic spin-orbit, were taken into account. For the mono-substituted-2-OH-pyridines studied in this work, coupling constants were calculated using both the optimized keto and enol forms. The possible use of these couplings as probes to detect the keto and enol forms is discussed.
format JOUR
author De Kowalewski, D.G.
Contreras, R.H.
Díez, E.
Esteban, A.
author_facet De Kowalewski, D.G.
Contreras, R.H.
Díez, E.
Esteban, A.
author_sort De Kowalewski, D.G.
title NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study
title_short NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study
title_full NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study
title_fullStr NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study
title_full_unstemmed NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study
title_sort nmr j(c,c) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-oh-n-x-pyridines. an experimental and dft study
url http://hdl.handle.net/20.500.12110/paper_00268976_v102_n23-24_p2607_DeKowalewski
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AT contrerasrh nmrjccscalarcouplinganalysisoftheeffectsofsubstituentsontheketoenoltautomericequilibriumin2ohnxpyridinesanexperimentalanddftstudy
AT dieze nmrjccscalarcouplinganalysisoftheeffectsofsubstituentsontheketoenoltautomericequilibriumin2ohnxpyridinesanexperimentalanddftstudy
AT estebana nmrjccscalarcouplinganalysisoftheeffectsofsubstituentsontheketoenoltautomericequilibriumin2ohnxpyridinesanexperimentalanddftstudy
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